http://123.206.87.240:8002/post/

题解：

工具：开发者工具

$what=$_POST['what'];
echo $what;
if($what=='flag')
echo 'flag{****}';

审查元素

修改HTML

<body>$what=$_POST['what'];<br>
echo $what;<br>
if($what=='flag')<br>
echo 'flag{****}';<br>
<form action="http://123.206.87.240:8002/post/" method="post">
    <input type="text" name="what">
  	<input type="submit" name="提交">
</form>
</body>

 

提交what=flag